PHOENIX -- Physical exam found a much a higher rate of thyroid cancer compared with incidental detection on imaging studies, researchers said here.
Among 200 consecutive patients presenting with thyroid nodules, 37.5% were found on physical examination and 33.5% were found incidentally on imaging studies, reported Robert Levine, MD, of the Thyroid Center of New Hampshire in Nashua, at the annual meeting of the American Association of Clinical Endocrinologists.
Among those, 12 cases were surgically confirmed as cancer, with 58% initially detected during physical examination and 25% found by the patient.
"Thus 9% of the nodules found at physical exam were malignant while only 1.5% of those found incidentally at other imaging were malignant," Levine and his co-author and daughter, Jessica Levine, a student at Tufts University in Boston, wrote.
An estimated 56,000 cases of thyroid cancer were diagnosed in the U.S. in 2012 and the number of biopsies performed went up to 450,000, paralleling this increase in cancer, the authors explained.
"We sought to evaluate how nodules were detected, and whether a correlation exists between method of detection and rate of malignancy," they said.
Levine told MedPage Today that "we thought at the start of this study that we would find that the vast majority of these nodules are found incidentally, but we were surprised to see that about one-third of them are discovered during physical examinations."
They reviewed medical records of 200 consecutive cases referred for thyroid nodules, and the mode of discovery of the nodule was determined from medical records. Additional information reviewed were size and number of nodules, whether a biopsy was performed, and if biopsied, whether benign or malignant.
Among the nodules found with imaging, 35 were seen on CT scans and 16 were discovered during MRI scans. Seventeen percent were found when a thyroid ultrasound was ordered for other reasons, such as an abnormal thyroid function test.
In 47 of 200 cases, biopsy was not performed, either because the nodule did not meet current guidelines for biopsy based on size and lack of suspicious sonographic features, or because of the patient's age and comorbidities.
In nine cases, biopsies were not done because of the presence of Hashimoto's thyroiditis without suspicious nodules.
Two patients had benign biopsies prior to consultation and in two other cases, no nodule was present.
Within the cancer cases, 67% were lymph node negative and 33% had positive lateral lymph nodes. Three cases were staged as T2N1bM0 and one was staged as T3N1bM1.
"While prior studies have suggested that the mode of discovery has no impact on the probability of the nodule being malignant, this study found a much higher rate of cancer in cases found by physical exam compared with those detected incidentally on other imaging studies," they concluded.
"We need guidelines that can help us decrease the number of biopsies performed after incidental nodules are found when imaging other sites," Levine added. "We need to know which nodules can be observed without biopsy."
Commenting on the study, Farhad Zangeneh, MD, a private practice endocrinologist in Sterling, Va., told MedPage Today that "when I find a thyroid nodule, I biopsy it. I think that my patients want that as well."
Zangeneh suggested that needle biopsies should be considered similar to Pap smears for cervical cancer -- a simple test to assess for potential disease. He said that he monitors his patients closely even after a negative finding. He pointed out that one of his patients underwent serial fine needle aspiration (FNA) biopsies over a period of months and that a malignancy was determined after the third biopsy.
"Reports like [the current study] are quite useful in helping the clinician decide what to do with these nodules, which are most likely benign and are extremely common," he said. "However, FNA is certainly a good tool to tell us what to do next."
The study authors and Zangeneh reported no conflicts of interest.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
American Association of Clinical EndocrinologistsSource Reference: Levine R, Levine J "Epidemic of thyroid nodules. How are they being dound?" AACE 2013; Abstract 1048.